RV Size and Systolic Function

Question 1

When in the cardiac cycle are RV measurements performed?

Answer 1

• Measured at end-diastolic frame: at or immediately prior to TV coaptation
• A4C RV focussed view

Question 2

Reference values for RV dilatation?

Answer 2

Dilatation when:

• Basal diameter > 41mm
• Mid diameter > 35mm
• Length > 83mm

Question 3

Qualitative indication for normal RV size?

Answer 3

RV area or mid-cavity diameter should be smaller than that of the LV

Question 4

Qualitative indication for mild RV dilatation?

Answer 4

• RV cavity area is increased (>2/3 of LV) but still smaller than LV
• LV forms apex

Question 5

Qualitative indication for moderate RV dilatation?

Answer 5

RV cavity area is similar to that of the LV and shares the apex of the heart

Question 6

Qualitative indication for severe RV dilatation?

Answer 6

• RV cavity area exceeds that of the LV

- RV will be apex forming

Question 7

Formula for RV fractional area change?

Answer 7

FAC (%) = (RVED area - RVES area) / RVED area x 100

- Normal FAC ≥35%

Question 8

Limitations of RV FAC?

Answer 8

1. Drop out of lateral wall makes measurement difficult
2. Heavy trabeculations of RV wall
3. Complex RV geometry - cannot capture inflow and outflow in same plane = difficult to model geometrically

Question 9

Normal measures of RV systolic function?

Answer 9

• FAC; normal ≥ 35%

- EF; normal ≥ 45%

Question 10

Measures of longitudinal RV systolic function?

Answer 10

• TAPSE: normal ≥ 17mm
• s’ velocity (DTI): normal ≥ 9.5cm/s
• Strain (GLS): normal is more negative than -20%

Question 11

Measure of global RV function?

Answer 11

• MPI via PWD or DTI
• Normal PW-MPI ≤ 0.4
• Normal DTI-MPI ≤ 0.55

Question 12

Limitations of TAPSE and DTI s’?

Answer 12

• Assumes function at basal lateral wall = overall RV systolic function
• Angle of intercept
• DTI: measuring IVC spike instead of s’

Question 13

Limitations of RV GLS?

Answer 13

• Differences in algorithms between vendors
• Variations in ‘normal’ values between platforms
• Technical challenges due to thinner RV wall

Question 14

Formula for MPI?

Answer 14

MPI = (IVCT + IVRT) / ET

Note: all units are in ms

Question 15

Effect of diastolic dysfunction on MPI?

Answer 15

• IVCT and IVRT increase with diastolic dysfunction
• ET decreases with diastolic dysfunction
• This all results in an increase in MPI due to diastolic dysfunction

Question 16

PW-MPI Formula with TV/RVOT trace?

Answer 16

• MPI = (TVc-o – ET) / ET
• TVc-o can be measured from TV closure to opening on TV inflow trace or measured as the TR duration in the presence of TR
• ET is measured as RVOT signal duration
• Normal PW-MPI ≤ 0.4

Question 17

DTI-MPI Formula?

Answer 17

• MPI = (a’-e’) – ET / ET
• a’-e’ measured on DTI from onset of IVC spike to just before e’ where trace dips below the baseline
• ET measures as s’ wave (excluding IVC spike)
• Normal DTI-MPI ≤ 0.55

Question 18

Limitation of RV MPI?

Answer 18

RV MPI psuedonormalises when RAP increases